Techniques for detecting inactive browser windows

ABSTRACT

Embodiments provide techniques for tracking the lifecycles of client-side browser windows in the context of a web application. In an embodiment, a server component of a web application can receive a notification that an application page in a first window has been unloaded. In response, the server component can associate the first window with an expiration time and add the first window to an expiration list of windows that are potentially inactive. If a request is received by the server component from the first window while the first window is in the expiration list, the server component can identify the first window as active and remove it from the list. If a request is received by the server component from a second window after the expiration time associated with the first window, the server component can identify the first window as inactive and free all resources for the first window.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. Pat. No. 8,892,635 filed on Jan. 6, 2011. The present disclosure is also related to the following commonly assigned, co-pending U.S. patent application, which is incorporated herein by reference in its entirety for all purposes: application Ser. No. 12/985,799, entitled “TECHNIQUES FOR DETECTING NEW BROWSER WINDOWS.”

BACKGROUND

The present disclosure relates in general to web applications, and in particular to techniques for tracking the lifecycles of client-side browser windows in such applications.

Generally speaking, a web application is a software application that is hosted on a server and is accessible by users via a client-side web browser. In a typical use case, a user opens a client-side browser window and navigates to an initial web page of the application. From there, the user can input information (e.g., via form elements embedded in the page markup) and/or navigate to additional pages of the application to complete some task or transaction.

In some instances, the user may open a new browser window from the context of an existing browser window while accessing the application. This causes the browser to send a new request to the server for the application page displayed in the existing window. In current implementations, the server generally cannot distinguish between this new window event and a situation where the user has reloaded/refreshed the existing window—in either case, the request received by the server appears to originate from the existing window. This can be problematic since the server typically maintains separate application state information for each browser window, and accordingly needs to know which window it is serving before rendering a page. For example, if the server erroneously determines that a client request corresponds to a reload of an existing window (when it actually corresponds to the opening of a new window), the server may unintentionally modify the application state of the existing window when processing the request.

In other instances, the user may close a browser window that he/she has used for accessing the application, or navigate away from the application (e.g., to a third party web site) within the window. In current implementations, the server generally cannot distinguish between these situations and a situation where the user has navigated (within the window) to another web page in the same application—in either case, the server simply receives a notification from the browser that the application page in the window has been unloaded/destroyed. This can make it difficult for the server to determine when to free memory resources (e.g., application state information) that are maintained by the server for each browser window. For example, if the server erroneously determines that a browser window is still being used to access the application (when the user has actually closed the window or navigated away from the application), the server may keep the resources for the window in memory longer than necessary, which is undesirable from both an efficiency and security standpoint.

BRIEF SUMMARY

Embodiments of the present invention provide techniques for tracking the lifecycles of client-side browser windows in the context of a web application. In one set of embodiments, a server component of a web application can receive a request originating from a client-side browser window, where the request includes a resource locator (e.g., a URL) and a window identifier. In response, the server component can send a script to the window for retrieving the window's actual identifier/name. Based on the actual identifier returned by the script and the window identifier included in the initial request, the server component can determine whether the window is a new window or an existing window and can process the request as appropriate.

In another set of embodiments, the server component can receive a notification that an application page in a first client-side browser window has been unloaded/destroyed. In response, the server component can associate the first window with an expiration time and can add the first window to an “expiration” list of windows that are potentially inactive (i.e., closed or no longer being used to accessing the application). If a new request is received by the server component from the first window while the first window is in the expiration list, the server component can identify the first window as active (i.e., still being used to accessing the application) and remove it from the list. If a new request is received by the server component from a second window while the first window is in the expiration list, the server component can compare the time at which the request from the second window was received with the expiration time associated with the first window. If the time of the request is later than the expiration time, the server component can identify the first window as inactive and free all resources associated with the first window.

In yet another set of embodiments, the server component can receive a notification that an application page in the last remaining window for the client-side browser has been unloaded/destroyed. In response, the server component can modify a session timeout variable for a user session associated with the browser from a first duration (e.g., one hour) to a second duration shorter that the first duration (e.g., ten minutes). The server component can then begin a countdown of the session timeout variable. If a request is received by the server component from the last remaining window before the second duration expires, the server component can identify the window as active and reset the session timeout variable to the first duration. If no request is received from the last remaining window before the second duration expires, the server component can identify the window as inactive, free all resources associated with the window, and free all resources associated with the user session.

According to one embodiment of the present invention, a method is provided that comprises maintaining, by a server computer system, a first list of windows open in a web browser running on a client computer system; receiving, by the server computer system, a notification from the web browser that an application page displayed in a first window in the first list has been unloaded; associating, by the server computer system, the first window with an expiration time; and adding, by the server computer system, the first window to a second list of windows, the second list including a subset of windows in the first list that are potentially inactive.

In one embodiment, the method further comprises receiving, by the server computer system from the web browser, a request originating from the first window; and identifying, by the server computer system, the first window as still being active.

In one embodiment, identifying the first window as still being active comprises removing the first window from the second list.

In one embodiment, the method further comprises receiving, by the server computer system from the web browser, a request originating from a second window in the second list; and identifying, by the server computer system, the second window as still being active.

In one embodiment, the method further comprises comparing, by the server computer system, a time at which the request was received with expiration time associated with windows in the second list; and if the time at which the request was received is later than a window's expiration time, identifying, by the server computer system, the window as being inactive.

In one embodiment, identifying the window as being inactive comprises removing the window from the first list and the second list; and freeing resources associated with the window.

In one embodiment, the method further comprises maintaining, by the server computer system, a session timeout variable for a user session associated with the windows open in the web browser, the session timeout variable being initialized to a first time period; determining, by the server computer system, that the last remaining window in the first list has been unloaded; and modifying, by the server computer system, the session timeout variable from the first time period to a second time period shorter than the first time period.

In one embodiment, the method further comprises, if a request originating from any window in the second list is received prior to expiration of the second time period, resetting, by the server computer system, the session timeout variable to the first time period, else freeing, by the server computer system, resources associated with the user session and the last remaining window.

In one embodiment, the method further comprises storing, by the server computer system for each window in the first list, an identifier of a current page loaded in the window.

According to another embodiment of the present invention, a non-transitory computer readable storage medium is provided having stored thereon instructions executable by a processor. The instructions include instructions that cause the processor to maintain a first list of windows open in a web browser running on a client computer system; instructions that cause the processor to receive a notification from the web browser that an application page displayed in a first window in the first list has been unloaded; instructions that cause the processor to associate the first window with an expiration time; and instructions that cause the processor to add the first window to a second list of windows, the second list including a subset of windows in the first list that are potentially inactive.

According to another embodiment of the present invention, a system is provided comprising a processor configured to maintain a first list of windows open in a web browser running on a client computer system; receive a notification from the web browser that an application page displayed in a first window in the first list has been unloaded; associate the first window with an expiration time; and add the first window to a second list of windows, the second list including a subset of windows in the first list that are potentially inactive.

A further understanding of the nature and advantages of the embodiments disclosed herein can be realized by reference to the remaining portions of the specification and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram illustrating a system in accordance with an embodiment of the present invention.

FIG. 2 is a flow diagram illustrating a process for determining whether a client-side browser window is a new window or an existing window in accordance with an embodiment of the present invention.

FIG. 3 is a flow diagram illustrating a process performed by a client-side script in accordance with an embodiment of the present invention.

FIG. 4 is a flow diagram illustrating a further process for determining whether a client-side browser window is a new window or an existing window in accordance with an embodiment of the present invention.

FIG. 5 is a flow diagram illustrating a process for determining whether a client-side browser window is inactive in accordance with an embodiment of the present invention.

FIG. 6 is a flow diagram illustrating a further process for determining whether a client-side browser window is inactive in accordance with an embodiment of the present invention.

FIG. 7 is a flow diagram illustrating a process for determining whether the last remaining window of a client-side browser is inactive in accordance with an embodiment of the present invention.

FIG. 8 is a simplified block diagram illustrating a system environment in accordance with an embodiment of the present invention.

FIG. 9 is a simplified block diagram illustrating a computer system in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

In the following description, for the purposes of explanation, numerous details are set forth in order to provide an understanding of embodiments of the present invention. It will be apparent, however, to one of ordinary skill in the art that certain embodiments can be practiced without some of these details.

Embodiments of the present invention provide techniques for tracking the lifecycles of client-side browser windows in the context of a web application. In one set of embodiments, a server component of a web application can receive a request originating from a client-side browser window, where the request includes a resource locator (e.g., a URL) and a window identifier. In response, the server component can send a script to the window for retrieving the window's actual identifier/name. Based on the actual identifier returned by the script and the window identifier included in the initial request, the server component can determine whether the window is a new window or an existing window and can process the request as appropriate.

In another set of embodiments, the server component can receive a notification that an application page in a first client-side browser window has been unloaded/destroyed. In response, the server component can associate the first window with an expiration time and can add the first window to an “expiration” list of windows that are potentially inactive (i.e., closed or no longer being used to access the application). If a new request is received by the server component from the first window while the first window is in the expiration list, the server component can identify the first window as active (i.e., still being used to accessing the application) and remove it from the list. If a new request is received by the server component from a second window while the first window is in the expiration list, the server component can compare the time at which the request from the second window was received with the expiration time associated with the first window. If the time of the request is later than the expiration time, the server component can identify the first window as inactive and free all resources associated with the first window.

In yet another set of embodiments, the server component can receive a notification that an application page in the last remaining window for the client-side browser has been unloaded/destroyed. In response, the server component can modify a session timeout variable for a user session associated with the browser from a first duration (e.g., one hour) to a second duration shorter that the first duration (e.g., ten minutes). The server component can then begin a countdown of the session timeout variable. If a request is received by the server component from the last remaining window before the second duration expires, the server component can identify the window as active and reset the session timeout variable to the first duration. If no request is received from the last remaining window before the second duration expires, the server component can identify the window as inactive, free all resources associated with the window, and free all resources associated with the user session.

FIG. 1 is a simplified block diagram illustrating a system 100 according to an embodiment of the present invention. As shown, system 100 can include a client 102 in communication with a server 104. Client 102 can be any type of electronic device or system (e.g., desktop computer, laptop computer, tablet computer, smartphone, personal digital assistant (PDA), set-top box, video game system, etc.) capable of running a web browser 106. Examples of available web browsers include Mozilla Firefox, Microsoft Internet Explorer, Google Chrome, Apple Safari, and the like. In various embodiments, web browser 106 can be operated by one or more users of client 102 to access web resources, such as a web application hosted by server 104.

In certain embodiments, web browser 106 can enable users to access multiple web resources simultaneously via multiple browser windows 108. For example, a user can open a first browser window in browser 106 and navigate to a first web page “A”. From the context of the first browser window, the user can open one or more additional (new) browser windows, thereby causing additional instances of web page A to be retrieved and rendered in the new windows. From there, the user can navigate to other web pages using any of the open windows. The user can also close one or more of the open windows once the user has finished his/her browsing session.

As used herein, the terms “browser window” and “window” can refer to any viewport of browser 106 capable of displaying web content identified by a resource identifier (e.g., a URL). In a particular embodiment, the terms “browser window” and “window” can refer to a browser “tab,” although such tabs are not typically considered to be standalone windows.

Server 104 can be any type of electronic device or system capable of hosting a web application such as application 114. In one set of embodiments, server 104 can include an application server component 110 configured to handle interactions between web browser 106 and web application 114 and to provide various services such as dynamic web page creation, load balancing, security, and the like. In a particular embodiment, application server 110 can include a web server component 112 configured to receive Hypertext Transfer Protocol (HTTP) requests from browser 106 of client 102 and to pass those requests to application server 110 and/or application 114 for processing. Web server 112 can also return HTTP responses (e.g., rendered HTML) to browser 106.

In one set of embodiments, application server 110 can be configured to track the lifecycles of client-side browser windows, such as windows 108 of web browser 106. For example, in one embodiment application server 110 can detect when a user of browser 106 has opened a new browser window while accessing application 114, and can distinguish that new window event from a reload/refresh event on an existing browser window. In another embodiment, application server 110 can detect when a user of browser 106 has inactivated a browser window by closing the window or navigating away from application 114, and can distinguish those situations from a situation where the user has merely navigated to another web page of application 114. The specific processing performed by application server 110 in these scenarios is described in detail with respect to FIGS. 2-7 below.

In addition to client 102 and server 104, system 100 can also include a data store 116. Data store 116 can be communicatively coupled with server 104 and can provide data storage services for various components of server 104, such as web application 114. Although server 104 and data store 116 are shown as separate entities in system 100, one of ordinary skill in the art will appreciate that server 104 and data store 116 can correspond to a single physical machine or separate physical machines.

It should be appreciated that FIG. 1 is illustrative and not intended to limit embodiments of the present invention. For example, the various entities of system 100 may each have additional capabilities or include additional components that are not specifically described. In addition, although only one client, one server, and one data store are depicted, any number of such entities can be supported. One of ordinary skill in the art will recognize many variations, modifications, and alternatives.

Detection of New Client-Side Browser Windows

As indicated above, in certain embodiments application server 110 can determine when a user of browser 106 has opened a new browser window while accessing application 114, and can distinguish that new window event from a reload/refresh event on an existing browser window. FIG. 2 illustrates a process 200 that can be performed by application server 110 for implementing this new window detection according to an embodiment of the present invention. In various embodiments, process 200 can be implemented in hardware, software, or a combination thereof. As software, process 200 can be encoded as program code stored on a machine-readable storage medium.

At block 202, application server 110 can receive an HTTP request originating from a window of client-side web browser 106, where the request is for a resource (e.g., web page) provided by web application 114. In various embodiments, the request can include an identifier of the resource (e.g., a URL), as well as an identifier of a particular browser window. For example, the request can include a URL “X” and a window identifier “Window1.” In most situations, the window identifier included in the request will correspond to the identifier of the browser window that originated the request. However, if the request originated from a new window created from the context of an existing window, the window identifier included in the request will correspond to the identifier/name of the existing window rather than the new window. Accordingly, in these cases application server 110 cannot readily discern, based on the window identifier alone, whether the originating window is a new or existing window.

At block 204, application server 110 can determine whether the request is an HTTP GET or HEAD request for a page of content from a user agent that supports JavaScript. If the request does not fall into this particular category, application server 110 can determine that the originating browser window is not a new window. Accordingly, application server 110 can performing its normal processing flow of rendering/retrieving content for the requested URL and sending a response to the browser window with the rendered/retrieved content (blocks 206, 208).

If the request is an HTTP GET or HEAD request for content from a user agent supporting JavaScript, application server 110 can further determine whether the request is a redirect (block 210). If the request is a redirect, application server 110 can perform the processing flow of blocks 206, 208 as described above.

If the request is not a redirect, application server 110 can determine that the request may have originated from a new browser window. In response, application server 110 can generate a proposed window identifier and a loopback identifier, and store the loopback identifier in a user session associated with the request (block 212). In one set of embodiments, the loopback identifier can be a randomly generated number. Application server 110 can further generate a client-side script that includes the loopback identifier, the proposed window identifier, and the URL and window identifier from the received request (e.g., “X” and “Window1”), and can send the script to the originating browser window (blocks 214, 216). In one set of embodiments, the client-side script can be configured to be uncacheable by client-side browser 106. The client-side script can then be executed by browser 106 to retrieve the actual identifier of the originating browser window, thereby facilitating determination of whether the originating window is a new or existing window.

FIG. 3 illustrates a process 300 that can be performed by web browser 106 upon receiving and executing the client-side script sent at block 214. At block 302, browser 106 can determine whether the window identifier included in the script (i.e., the window identifier extracted from the request received at block 202) matches the identifier/name of the current browser window (i.e., the window that originated the request). If the identifiers match, that indicates that the current window is an existing window. In this case, browser 106 can initiate a client-side redirect to send a second HTTP request to server 104 that mirrors the original HTTP request (e.g., includes URL “U1” and window identifier “Window1”), with the addition of the loopback identifier (block 304).

If the identifiers do not match, that indicates that the current window is a new window. In this case, browser 106 can determine whether there already exists a window identifier for the current window (block 306). For example, browser 106 may have automatically assigned a new name/identifier to the window upon opening it. If such an existing identifier is found, browser 106 can initiate a client-side redirect to send a second HTTP request to server 104, wherein the second request includes the loopback identifier, the URL, and the existing identifier (block 308). If an existing window identifier is not found, browser 106 can initiate a client-side redirect to send a second HTTP request that includes the loopback identifier, the URL, and the proposed window identifier generated at block 212 of FIG. 2 (block 310).

Upon receiving the second HTTP request sent by browser 106 at block 304, 308, or 310 of FIG. 3, application server 110 can carry out process 400 of FIG. 4. At blocks 402 and 404, application server 110 can receive the second HTTP request and match the loopback identifier included in the second request with the loopback identifier stored in the user's session. If the loopback identifiers match, the application server knows that this second request was generated in response to the client-side script sent at block 214 (rather than in response to a user action). Accordingly, application server 110 can remove the loopback identifier from the session (block 406) and proceed with the remainder of process 400.

At block 408, application server 110 can determine whether the window identifier included in the second request matches the window identifier included in the original request received at block 202. If the identifiers match, application server 110 can conclude that the window that originated the original request of block 202 is an existing window. Alternatively, if the identifiers do not match, server 104 can conclude that the window that originated the original request of block 202 is a new window. Application server 110 can then process the original request by rendering/retrieving the content for the URL and sending a response to the originating browser window that includes the rendered/retrieved content (blocks 414, 416).

In a particular embodiment, the processing of the original request can differ based on whether the originating window is determined to be a new window or an existing window. For example, if the originating window is determined to be an existing window per block 410, application server 110 can freely update/modify application state information associated with that window. However, if the originating window is determined to be a new window per block 412, application server 110 can take appropriate steps to ensure that the states of any existing windows remain unchanged. In this manner, application server 110 can avoid unintentionally trashing/invalidating the states of those existing windows when processing the request from the new window.

It should be appreciated that processes 200, 300, and 400 are illustrative and that variations and modifications are possible. For example, steps described as sequential may be executed in parallel, order of steps may be varied, and steps may be modified, combined, added, or omitted. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

Detection of Inactive Client-Side Browser Windows

In certain embodiments, application server 110 can detect when a user of browser 106 has inactivated a browser window by closing the window or navigating away from application 114, and can distinguish those situations from a case where the user has merely navigated to another web page of application 114. FIG. 5 illustrates a process 500 that can be performed by application server 110 for implementing this inactive window detection according to an embodiment of the present invention. In various embodiments, process 500 can be implemented in hardware, software, or a combination thereof. As software, process 500 can be encoded as program code stored on a machine-readable storage medium.

At block 502, application server 110 can maintain an “active” list of browser windows that are open in web browser 106. From the perspective of application server 110, a browser window is considered “active” if it is being used to access web application 114. The active list can be stored as part of the user session associated with the browser. In one set of embodiments, the entry for each window in the active list can include the window's identifier and an indication of the current page being displayed in the window.

At block 504, application server 110 can receive a notification from browser 106 that an application page in an active browser window has been unloaded/destroyed. Such a notification may be received if, e.g., the window has been closed by a user, or if the user has navigated to a different web page within the window. In response, application server 110 can associate an expiration time with the active window, and can add the window to an “expiration” list of windows that are potentially inactive (i.e., no longer being used to access the application) (blocks 506, 508).

In addition, application server 110 can determine whether all of the windows in the active list are now in the expiration list (block 510). If not, the steps of blocks 504-510 can be repeated as more unload/destroy notifications are received by application server 110, thereby causing additional active windows to be added to the expiration list. If all of the active windows are now in the expiration list, application server 110 can perform special processing to determine whether to free user session-level resources; this processing is discussed with respect to FIG. 7 below.

The processing of FIG. 5 is continued in process 600 of FIG. 6. At block 602, application server 110 can receive an HTTP request originating from a particular browser window that was previously placed in the expiration list at block 508. Since the receipt of this request indicates that the window is still being used to access application 114, application server 110 can conclude that the window is still active and can remove it from the expiration list (block 604). Application server 110 can also update the window's entry in the active list with the latest URL included in the received request.

At block 606, application server 110 can go through the remaining windows in the expiration list and compare, for each window, the time at which the request was received at block 602 with the expiration time associated with the window. If the time of the request is later than the expiration time for the window, application server 110 can identify the window as being inactive (i.e., no longer being used to access application 114) and can remove the window from both the active and expiration lists. Application server 110 can also free the memory resources (e.g., application state information, etc.) associated with that window.

If the time of the request is earlier than the expiration time for the window, application server 110 can leave the window in the expiration list. The window can remain in the expiration list until a new request is received from that window (indicating that the window is still active), or until a new request is received from a different window at a time later than the expiration time associated with the window (indicating that the window is most likely inactive).

In some cases when a user navigates from a first application page to a second application page in a browser window, application server 110 may receive a request for the second page before it receives the notification that the first page has been destroyed/unloaded. This is because HTTP does not guarantee that messages are received in the same order in which they were sent. To account for this, in certain embodiments application server 110 can keep track of the current page displayed in each window and can ignore unload notifications that pertain to outdated pages.

For example, assume browser window A is currently displaying application page 1. Further, assume that the user of window A navigates from application page 1 to application page 2, but application server 110 receives the request for (window A, page 2) before the unload notification for (window A, page 1). Once the request for (window A, page 2) is received, application server 110 can update the active window list such that the current page for window A is page 2. When the unload notification for (window A, page 1) is subsequently received, application server 110 can ignore the unload notification since the current page for window A is not page 1 (rather, it is page 2). Thus, this prevents application server 110 from erroneously adding window A to the expiration list upon receiving the unload notification.

It should be appreciated that processes 500 and 600 are illustrative and that variations and modifications are possible. For example, steps described as sequential may be executed in parallel, order of steps may be varied, and steps may be modified, combined, added, or omitted. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

As noted above, in certain embodiments application server 110 can employ special processing to detect when the last remaining browser window for a user session has been inactivated/closed. This processing is illustrated in process 700 of FIG. 7. In various embodiments, process 700 can be implemented in hardware, software, or a combination thereof. As software, process 700 can be encoded as program code stored on a machine-readable storage medium.

At block 702, application server 110 can determine that an application page in the last remaining browser window for a user session (i.e., the last window in the active list) has been unloaded/destroyed. In one set of embodiments, this can be accomplished by comparing the set of windows in the active list and the expiration list are the same. Upon determining that the last remaining browser window has been unloaded/destroyed, application server 110 can modify a session timeout variable associated with the user session from a first time period (e.g., one hour) to a second time period shorter than the first (e.g., ten minutes), and can begin a countdown of the variable (block 704).

If a HTTP request is received from any window before the session timeout variable expires, application server 110 can conclude that the session is still active and can reset the session timeout variable to the first time period (blocks 706, 708). Further, processing can return to block 602 of FIG. 6.

However, if no request is received from any window before the session timeout variable expires, application server 110 can conclude that the last remaining window is inactive (and thus, the entire user session is closed). Accordingly, application server 110 can free all of the resources associated with the window and the user session (block 710).

It should be appreciated that process 700 is illustrative and that variations and modifications are possible. For example, steps described as sequential may be executed in parallel, order of steps may be varied, and steps may be modified, combined, added, or omitted. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

FIG. 8 is a simplified block diagram illustrating a system environment 800 according to an embodiment of the present invention. As shown, system environment 800 can include one or more client computer systems 802, 804, 806, 808, a server computer system 810, a network 812, and a database 814. In various embodiments, client computer systems 802, 804, 806, 808, server computer system 810, and database 814 can be used to implement client 102, server 104, and data store 116 of FIG. 1 respectively.

Client computer systems 802, 804, 806, 808 can be general-purpose personal computers (e.g., desktop computers and/or laptop computers), tablet computers, smart phones, PDAs, and/or workstation computers. Alternatively, client computer systems 802, 804, 806, 808 can be any other type of electronic device capable of running a web browser such as browser 106 of FIG. 1. Although system environment 800 is shown with four client computer systems, it should be appreciated that any number of client computer systems can be supported.

Network 812 can be any type of network familiar to those skilled in the art that can support data communications using a network protocol, such as TCP/IP, SNA, IPX, AppleTalk, and the like. Merely by way of example, network 812 can be a local area network (LAN), such as an Ethernet network; a wide-area network; a virtual network, including without limitation a virtual private network (VPN); the Internet; a wireless network (e.g., a network operating under any of the IEEE 802.11 suite of protocols, the Bluetooth protocol known in the art, and/or any other wireless protocol); and/or any combination of these and/or other networks.

Server computer system 810 can be a general purpose computer, a specialized server computer (e.g., PC server, UNIX server, mainframe server, rack-mounted server, etc.), a server cluster, or any other appropriate arrangement and/or combination of computers. Server computer system 810 can run any consumer or server operating system such as Microsoft Windows, Apple OS X, Linux, Solaris, and the like. Server computer system 810 can also run any of a variety of server applications and/or mid-tier applications, including application server 110 and web application 114 of FIG. 1.

Database 814 can reside on a storage medium local to (and/or resident in) one or more of computer systems 802, 804, 806, 808, and 810. Alternatively, database 814 can be remote from any or all of computer systems 802, 804, 806, 808, 810, and/or in communication (e.g., via network 812) with one or more of these. In one set of embodiments, database 814 can reside in a storage-area network (SAN) familiar to those skilled in the art. Similarly, any necessary files for performing the functions attributed to computer systems 802, 804, 806, 808, 810 can be stored locally on the respective computer and/or remotely on database 814, as appropriate. In one set of embodiments, database 814 can be a relational database, such as Oracle 11g available from Oracle Corporation, that is adapted to store, update, and retrieve data in response to SQL-formatted commands

FIG. 9 is a simplified block diagram illustrating a computer system 900 according to an embodiment of the present invention. In various embodiments, computer system 900 can be used to implement any of computer systems 802, 804, 806, 808, and 810 described with respect to system environment 800 above. As shown, computer system 900 can include hardware elements that are electrically coupled via a bus 924. The hardware elements can include one or more central processing units (CPUs) 902, one or more input devices 904 (e.g., a mouse, a keyboard, etc.), and one or more output devices 906 (e.g., a display device, a printer, etc.). Computer system 900 can also include one or more storage devices 908. By way of example, the storage device(s) 908 can include devices such as disk drives, optical storage devices, and solid-state storage devices such as a random access memory (RAM) and/or a read-only memory (ROM), which can be programmable, flash-updateable and/or the like.

Computer system 900 can additionally include a computer-readable storage media reader 912, a communications subsystem 914 (e.g., a modem, a network card (wireless or wired), an infra-red communication device, etc.), and working memory 918, which can include RAM and ROM devices as described above. In some embodiments, computer system 900 can also include a processing acceleration unit 916, which can include a digital signal processor (DSP), a special-purpose processor, and/or the like.

Computer-readable storage media reader 912 can be connected to a computer-readable storage medium 910, together (and, optionally, in combination with storage device(s) 908) comprehensively representing remote, local, fixed, and/or removable storage devices plus storage media for temporarily and/or more permanently containing computer-readable information. Communications system 914 can permit data to be exchanged with network 812 and/or any other computer described above with respect to system environment 800.

Computer system 900 can also comprise software elements, shown as being currently located within working memory 918, including an operating system 920 and/or other code 922, such as an application program (which may be a client-side web browser, middle tier/server application, etc.). It should be appreciated that alternative embodiments of computer system 900 can have numerous variations from that described above. For example, customized hardware can be used and particular elements can be implemented in hardware, software, or both. Further, connection to other computing devices such as network input/output devices can be employed.

Computer readable storage media for containing code, or portions of code, executable by computer system 900 can include any appropriate media known or used in the art, such as but not limited to volatile/non-volatile and removable/non-removable media. Examples of computer-readable storage media include RAM, ROM, EEPROM, flash memory, CD-ROM, digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, an any other medium that can be used to store data and/or program code and that can be accessed by a computer.

Although specific embodiments of the invention have been described above, various modifications, alterations, alternative constructions, and equivalents are within the scope of the invention. For example, although embodiments of the present invention have been described with respect to certain flow diagrams and steps, it should be apparent to those skilled in the art that the scope of the present invention is not limited to the described diagrams/steps.

Further, although embodiments of the present invention have been described using a particular combination of hardware and software, it should be recognized that other combinations of hardware and software are also within the scope of the present invention.

The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense. It will be evident that additions, subtractions, and other modifications may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the following claims. 

What is claimed is:
 1. A method comprising: maintaining, by a computer system, a first list of windows open in a web browser running on a client computer system, at least a first window of the first list of windows being associated with a first window identifier, the first window identifier identifying a first application page, the first list of windows including a subset of windows that are capable of being active; receiving a request to access a second application page displayed in the first window; updating, by the computer system, the first window identifier to identify the second application page; receiving a notification from the web browser that the first application page displayed in the first window in the first list of windows has been unloaded; and retaining the first window in the first list of windows without adding the first window to a second list of windows, the second list of windows including a subset of windows in the first list of windows that are capable of being inactive.
 2. The method of claim 1, wherein the request to access the second application page is received prior to receiving the notification that the first application page has been unloaded.
 3. The method of claim 2, further comprising: determining, by the computer system, that the first window identifier identifies the second application page upon receiving the notification that the first application page has been unloaded; and retaining the first window in the first list of windows based at least in part on the determining.
 4. The method of claim 1, further comprising: receiving, by the computer system, a notification from the web browser that an application page displayed in a first window in the first list has been unloaded; associating, by the computer system, the first window with an expiration time; and adding, by the computer system, the first window to a second list of windows, the second list including a subset of windows in the first list that are capable of being inactive.
 5. The method of claim 1, further comprising: receiving, from the web browser, a request originating from the first window; identifying, by the computer system, the first window as still being active; and removing the first window from the second list of windows.
 6. The method of claim 1, further comprising: receiving, from the web browser, a request originating from a window in the second list of windows; comparing, by the computer system, a time at which the request was received with an expiration time associated with the second list of windows; and if the time at which the request was received is later than the expiration time, identifying, by the computer system, the window as being inactive.
 7. The method of claim 6, wherein identifying the window as being inactive comprises: removing the window from the first list of windows and the second list of windows; and making resources associated with the window available.
 8. The method of claim 1, further comprising: maintaining, by the computer system, a session timeout variable for a user session associated with one or more windows open in the web browser, the session timeout variable being initialized to a first time period; determining, by the computer system, that an application page in a last remaining window in the first list of windows has been unloaded; and modifying the session timeout variable from the first time period to a second time period based at least in part on the determining, the second time period being shorter than the first time period.
 9. The method of claim 8, further comprising: if a request originating from a window in the first list of windows or the second list of windows is received prior to the expiration of the second time period, resetting, by the server computer system, the session timeout variable to the first time period, else freeing, by the server computer system, resources associated with the user session and the last remaining window.
 10. A non-transitory computer readable storage medium having stored thereon instructions executable by a processor, the instructions including: instructions that cause the processor to maintain a first list of windows open in a web browser running on a client computer system, at least a first window of the first list of windows being associated with a first window identifier, the first window identifier identifying a first application page, the first list of windows including a subset of windows that are capable of being active; instructions that cause the processor to receive a request to access a second application page displayed in the first window; instructions that cause the processor to update the first window identifier to identify the second application page; instructions that cause the processor to receive a notification from the web browser that the first application page displayed in the first window in the first list of windows has been unloaded; and instructions that cause the processor to retain the first window in the first list of windows without adding the first window to a second list of windows, the second list of windows including a subset of windows in the first list of windows that are capable of being inactive.
 11. The non-transitory computer readable storage medium of claim 10, wherein the instructions to receive the request to access the second application page are received prior to the instructions to receive the notification that the first application page has been unloaded.
 12. The non-transitory computer readable medium of claim 11, wherein based upon receiving the notification that the first application page has been unloaded, the instructions further comprise: instructions that cause the processor to determine that the first window identifier identifies the second application page; and instructions that cause the processor to retain the first window in the first list of windows.
 13. The non-transitory computer readable medium of claim 10 wherein the instructions further comprise: instructions that cause the processor to maintain a session timeout variable for a user session associated with one or more windows open in the web browser, the session timeout variable being initialized to a first time period; instructions that cause the processor to determine that an application page in a last remaining window in the first list of windows has been unloaded; and based at least in part on the instructions to determine, instructions that cause the processor to modify the session timeout variable from the first time period to a second time period, the second time period being shorter than the first time period.
 14. The non-transitory computer readable medium of claim 13, wherein the instructions further comprise instructions that cause the processor to reset the session timeout variable to the first time period if the request originating from a window in the first list of windows or the second list of windows is received prior to expiration of the second time period.
 15. The non-transitory computer readable medium of claim 14, wherein the instructions further comprise instructions that cause the processor to free resources associated with the user session and the last remaining window if no request originating from a window in the first list of windows or the second list of windows is received prior to the expiration of the session timeout variable.
 16. A system comprising: a processor configured to execute computer executable instructions to collectively at least: maintain a first list of windows open in a web browser running on a client computer system, at least a first window of the first list of windows being associated with a first window identifier, the first window identifier identifying a first application page, the first list of windows including a subset of windows that are capable of being active; receive a request to access a second application page displayed in the first window; update the first window identifier to identify the second application page; receive a notification from the web browser that the first application page displayed in the first window in the first list of windows has been unloaded; and retain the first window in the first list of windows without adding the first window to a second list of windows, the second list of windows including a subset of windows in the first list of windows that are capable of being inactive.
 17. The system of claim 15, wherein the processor is further configured to receive the request to access the second application page prior to receiving the notification that the first application page has been unloaded.
 18. The system of claim 15, wherein the processor is further configured to: determine that the first window identifier identifies the second application page based upon receiving the notification that the first application page has been unloaded; and retain the first window in the first list of windows.
 19. The system of claim 15, wherein the processor is further configured to: receive from the web browser a request originating from the first window; identify the first window as still being active; and remove the first window from the second list of windows.
 20. The system of claim 15, wherein the processor is further configured to: receive a request originating from a window in the second list of windows; compare a time at which the request was received with an expiration time associated with the second list of windows; and if the time at which the request was received is later than the expiration time, identify the window as being inactive. 